To their credit, most Democratic Party leaders have (finally) called for New York Rep. Anthony Weiner’s resignation. But among liberal commentators and millions of other Americans, there is a great deal of flawed thinking about whether Weiner should resign.

The two most common arguments offered against his resigning have been that (1) what Weiner did was not illegal and (2) it was not even as bad as an extramarital affair because he never met, let alone had physical contact with, any of the women to whom he sent naked and semi-naked photos of himself.

The argument’s entirely beside the point.

The point — the whole point — is the effect of what he did on the United States House of Representatives and on the country as a whole, especially young people.

There is a simple way to prove this. Let us imagine that some congressman had walked onto the House floor in his underwear. I think it is fair to assume that just about every Democrat and Republican in the country would demand his resignation. But why? That action is not illegal, and it certainly does not constitute a form of infidelity to his wife.

The reason people would demand his resignation is that such behavior disgraced the House of Representatives.

That is the issue here. When a member of Congress sends pictures of his penis to women around the country, he has demeaned Congress.

And he has done so far more than any member of Congress whose extramarital affair was publicly disclosed.

Most Americans understand that Congress, like every other institution, including their local church and synagogue, is composed of sinners. While we might wish that every member of Congress were as upstanding as we hope our pastor, priest or rabbi would be, most of us live in the real world and do not believe that marital infidelity automatically disqualifies one either from running for, or from holding, public office.

Furthermore, we understand that marital infidelity can be solely a matter between a husband and wife, and is not necessarily the country’s business.

But what Weiner did is the country’s business because of its effect on the reputation of the House and because of its effect on young Americans.

If I were a member of Congress, I would not be livid at every one of my colleagues who had had an affair. But I would be livid at Weiner. Every day he remains a congressman, he makes every one of his colleagues look bad: You can send photos such as Weiner did to women around America and still remain a member of this institution.

And at least as destructive as his impact on the House of Representatives is his impact on young America. The message to young Americans is the same: A 46-year-old member of Congress can send photos such as this congressman did to women around the country and keep his seat.

To appreciate how terrible this looks to a young person, ask your teenage son or daughter if he or she would be more humiliated if it became known that Dad had had an affair or that Dad sent photos of his penis to young women he never met.

I cannot think of a single event that symbolizes the decline of American society — and especially of its liberal elite — as much as Weiner’s actions and his retention of his seat in Congress.

It is almost surreal. The Weiner photos pervade the Internet, and people like Sen. Charles Schumer, D-N.Y., do not demand the congressman’s resignation, and liberal commentators wonder whether the congressman violated any laws.

Salon’s Joan Walsh on MSNBC: “You can’t accuse him of hypocrisy; he’s not a family values moralizer. You can’t accuse him yet of breaking the law.”

Los Angeles Times editorial, June 8: “We’d prefer to leave it to New York voters to decide Weiner’s political future.”

And surely the Los Angeles Times knows that a majority of New York City voters say Weiner should stay in office.

New York Times editorial, June 6: “Mr. Weiner says he will not resign, and there is no evidence yet that he broke the law or abused the resources of his office. He said the computer and BlackBerry that he used were his own, not issued by the government.”

If you ever need to show someone how low liberalism has sunk in our lifetime, just show him this New York Times editorial. A congressman sends photos of his genitalia to women he doesn’t know, and The New York Times doesn’t think he should resign unless the BlackBerry he used was issued by the government.

Dennis Prager hosts a nationally syndicated radio talk show and is a visiting fellow at the Hoover Institution at Stanford University. He is the author of four books, most recently “Happiness Is a Serious Problem” (HarperCollins). His website is www.dennisprager.com.